easily stopped e.g. by a sheet of paper or the outer layer of dead skin cells

beta penetrating power

stopped by thin (a few mm) metal sheet

gamma penetrating power

reduced intensity by 1/2 by about 5cm of concrete or 1cm of lead

.... fields can also be used to determine whether a sample of radioactive sample is emitting alpha , beta or gamma

magnetic

the major sources of background radiation are

air

rocks and buildings

cosmic rays

food and drink

medical

miscellaneous

air

this dose is mainly from radon and thorn , radioactive gases that are part of long lived decay series

rocks and buildings

some rocks particularly granite contain uranium-238 or thorium-232 . these two isotopes have long half lives and decay to other radioactive products . the radiation dose from this depends on where you live .